DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES - Commodity Derivative Instruments (Details) gal in Thousands	9 Months Ended
	Sep. 30, 2019 gal
Derivatives NOT Designated as Hedging Instruments | Physical fixed-price derivative contracts | Current
Derivative Instruments And Hedging Activities
Volume (in gallons)	14,544
Derivatives NOT Designated as Hedging Instruments | Physical fixed-price derivative contracts | Long-Term
Derivative Instruments And Hedging Activities
Volume (in gallons)	879
Derivatives NOT Designated as Hedging Instruments | Physical index derivative contracts | Current
Derivative Instruments And Hedging Activities
Volume (in gallons)	677
Derivatives NOT Designated as Hedging Instruments | Physical index derivative contracts | Long-Term
Derivative Instruments And Hedging Activities
Volume (in gallons)	0
Derivatives NOT Designated as Hedging Instruments | Futures contracts for refined petroleum products | Current
Derivative Instruments And Hedging Activities
Volume (in gallons)	26,622
Derivatives NOT Designated as Hedging Instruments | Futures contracts for refined petroleum products | Long-Term
Derivative Instruments And Hedging Activities
Volume (in gallons)	1,638
Derivatives Designated as Hedging Instruments | Cash Flow Hedge | Physical index derivative contracts | Current
Derivative Instruments And Hedging Activities
Volume (in gallons)	2,946
Derivatives Designated as Hedging Instruments | Cash Flow Hedge | Physical index derivative contracts | Long-Term
Derivative Instruments And Hedging Activities
Volume (in gallons)	0
Derivatives Designated as Hedging Instruments | Cash Flow Hedge | Cash flow hedge futures contracts | Current
Derivative Instruments And Hedging Activities
Volume (in gallons)	29,652
Derivatives Designated as Hedging Instruments | Cash Flow Hedge | Cash flow hedge futures contracts | Long-Term
Derivative Instruments And Hedging Activities
Volume (in gallons)	0
Derivatives Designated as Hedging Instruments | Fair Value Hedge | Futures contracts for refined petroleum products | Current
Derivative Instruments And Hedging Activities
Volume (in gallons)	50,568
Derivatives Designated as Hedging Instruments | Fair Value Hedge | Futures contracts for refined petroleum products | Long-Term
Derivative Instruments And Hedging Activities
Volume (in gallons)	0